Int. J. N
oxide direc form mono resul fluen Key PAC
distin nove large semi depe synth quan excit chara partic nano treatm techn recog are ty
* ) For
Nanoelectronic
Metal o fabrica
Evan T.
1Universi
2Universi
Received
Abstrac In the pr e Nanoparti ct spraying mation of he ocrystalline lt also show ncy number
words: ZnO CS: 31.15.xr
1. Intro
Nanostru nguished pe el electrical ely believed
conductors, nds on the hesized with ntum-size ef
ZnO nan ton binding acteristics b cles have t oparticles ar ment, cataly Among nique has gnizance as ypical exam
r corresponde
cs and Materials
oxide nan ation
Salem*,1, M ity of Techno ity of Techno
d 5 Dec. 20
ct
resent work icles suspen
of the pre eterojunctio es ZnO nano w a direct
of laser pul O Nanopart r, 68.37.Yz,
oduction uctured Zn erformance l, mechanic d to be res , such as Z e semicond
h dimension ffects occur noparticles d g energy o
because of the large su re used in yst, photo c
different p been succ s an import mples of top
ence, E-mail: e
s 6 (2013) 121-
noparticle
Makram A. F ology, Applie ology, Laser
11; Revised
k, simple an nsion, this d epared collo on device. T oparticles w depended o lse and lase ticles, LP-PL , 61.46.Df, 6
nO materia in electroni cal, chemic sult of surf ZnO the el ductor’s die ns smaller t
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do not only f 60 mev the particu urface-to-vo
a variety o atalyst and reparation cessfully d tant techniq p-down app
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es suspens
Fakhry2, Ha ed Science D
and Optoele
d 9 May 20
nd single st done by las oidal suspe The x-ray d with a wirtiz of the parti er waveleng LA, AFM, 61.46.Km,
als have nic, optics an
cal and opt face and qu
lectron and electric con than the nat
have the m and excell ularity of n
olume ratio of applicati others [3].
methods fo developed que for the proach in fa
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ep method ser ablation ension on s diffraction ze structure icle size on
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Device fabr 81.07.-b, 85
received b nd photonic ical proper uantum qua d hole orbit nstant. Whe tural exciton merits of ZnO
lent stabilit nanostructur
o and surfa ions such a or producin
and laser fabrication abrication o
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Laser Science artment, Bag
ed 23 July 2
has been u n of pure m silicon subs
results insu e. The atom n laser para
rication.
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ty, but also re, it is we ace defect [ as UV abso ng Nanopart ablation i of Nanopa f Nanoparti
onic devic
e Branch, Ba ghdad, Iraq.
2012
used to prep metal in liqu strate leadin ure the form mic force mi
ameter such
ntion due ith reduction troduced, w effects [1]
er at a dist nductor par alled the Bo ductor such
o have som ell known t
[2], thus Z orption, ant rticles, laser in liquid h articles. Thi
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aghdad, Iraq
pare metal uid. While ng to the mation of icroscopic h as laser
to their n in size, which are ]. In bulk tance that rticles are hr radius)
as a large me novel that small inc oxide tibacterial r ablation has been is method ulsed laser
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Evan T. Sale
122 ablation Nanomat plasma a Nanopart Applicati studied.
In
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H at the bo YAG las focusing continuou on the fr ablation t order to g an oven nanoparti
Fig. 1: E
em, et al. / Met
in liquid m terials via r
and liquid.
ticles (NPs ion of such n this work
l and surf on was depe
. Experim High purity ( ttom of an ser system
20 cm co usly transla resh surface traces or cru get homoge n at 60 ᵒC icles thin fil
Experimenta 2
tal oxide nanop
media (PLAL rapid reactiv . PLAL is s) such as nanopartic effect of las face morph
ended for op
mental Wor (1×1 cm) (9
open plasti type (HU onverging l ated mechan
e and ablat usts. The co eneity for th C temperatu lms as show
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L) is a prom ve quenchin s a versati s noble m les colloida ser fluency hology was ptoelectroni
k
99.99) Zn p c cell conta AFEI) at d lens as sho nically usin
tes the targ olloidal solu he product, ure in ord wn in Fig. 2
anoparticles ng lens, 3) C
sion for optoele
mising tech ng of ablate ile techniq metals, alloy
al in optoele number of s present, o
ic device fa
plate from ( aining (3 m different la ow in Fig.
ng a controll get surface ution vibrat and then d der to con , this metho
synthesis, by Container cell
ectronic devises
hnique for th ed species a
ue. For pr ys, oxides ectronic dev
laser pulse optimum c abrication.
Fluke) was ml DIW). An aser fluence 1. The po led motor s
homogeneo ted for 10 m dropped on
vert ZnO od was depe
y laser ablati l, 4) Rotating
s fabrication
he controlle at the interf reparing va
and semi vice was no
and laser w condition fo
used as a t nd ablated u
e (48, 71 osition of m
o that each ously also min by ultra the glass su
nanoparticl ended in oth
ion technique g motors.
ed fabricati face betwee arious kind iconductors ot yet extens wavelength o for nanopar
target, so it using pulsed
and 142) metal plate h laser pulse to avoid a asonic vibra
ubstrate, dri les colloid her work [6]
e, 1) Laser h ion of en the ds of s [5].
sively on the rticles
fixed d Nd-
J/cm2 e was e falls
deep ator in ied in dal to
]
head,
Int. J. Nanoelectronics and Materials 6 (2013) 121-128
123 Fig. 2: The drop drying method.
In order to explain the structural properties, the nature and the crystal growth of the dried films at different preparation conditions, X-ray diffraction measurement has been done according to the ASTM (American Society of Testing Materials) cards, using Philips PW 1050 X-ray diffract meter of 1.54 Å from Cu-k. The particle size distributions of the nanoparticles prepared under various conditions were analyzed using atomic force microscope (AFM). The surface morphological studies of the ZnO nanoparticles were conducted by tapping mode atomic force microscopy (AFM) from (AA3000). For device fabrication Simply by Direct spraying of the ZnO NPs colloidal using a glass nozzle connected with an air compressor on Si wafer surface heated to 150 ᵒC to obtain an uniform distributed Nanoparticles thin film, and hence heterojunction ZnO/ p-Si was obtained. For heterojunction devise characterization A Kiethley-616 electrometer was used to measure the flow current in a solar cell manufactured from the produced structure in dark condition as voltage been applied from a Farnell power supply of range (0.2-3) V in forward biasing and reverse biasing.
3. Result and Discussion
The XRD patterns of the ZnO NPs formed by laser ablation of a Zn plate in DIW at room temperature at laser flunce (48, 71 and 142) J/cm2 are shown in Fig. 3a, b and c. At laser fluence of (43 J/cm2) a very week diffraction peak apear at (100) diffraction plane, with increase laser power density, due to increase the amount of the ablated material, we could recognize the peak lacated at 2 = 32.37 with lattice constant of (2.76o). By increasing the laser flunce up to (71 J/cm2) Fig. (b) a specific sharp peak apear due to the diffraction from the same plane which located at 2=30.015o with coresponding latice constant (2.97o). With farther increas in the laser fluncy Fig. (c) the diffraction peaks still sharp and specific.
Evan T. Salem, et al. / Metal oxide nanoparticles suspension for optoelectronic devises fabrication
124
(a)
(b)
(c)
Fig. 3: X-ray diffiraction result for ZnO NPs prepared using 1.06 m wavelength at different laser flency (a-43, b-71, c-142) J/cm2.
The surface morphology of ZnO Nanoparticles colloidal prepared by LP-PLA at laser flunce was obtain using Atomic force microscopic images. Multi- drop of the colloidal suspension was drying on glass substrate at 60 Co. Fig. 4a, b, and c show the particle size distribution and nanoparticles topography of drying colloids prepared at different laser fluency (43, 71 and 142 J/cm2) the surface morphology and hens particles size distribution could be recognize. It's clearly obvious the increase in the particles size with increasing the laser fleuence, this attributed to the effect of laser power on the states of the plasma during the laser ablation process in liquid. This is related to the overall process of the oxide nanostructure formation by LP-PLA mechanism. Briefly comprise three different but almost coinstantaneous process [7] the first one is the instantaneous initiation, short-lived persistence and rapid annihilation of the local plasma with HTHP (high temperature and high pressure). The second is the nucleation and growth of the species during and after the annihilating period. The last one is the aqueous oxidation and quenching of the formed clusters. It can be seen that the state of plasma play a basic and decisive role in such
insta work time and h powe beco
Fig. 4
antaneous fo k, it can attr
and intensi has a relativ er and envir
me more ob
4: Surface m Aver
Averag 39
Averag 4
ormation mo ributed to th
ity of plasm vely low te ronmental d bvious.
morphology o fluen age particle si 36.31 (nm)
ge particle size 9.11 (nm)
ge particle size 45.91 (nm)
ode. As to t he effect of ma. In case o emperature a
disturbance
of ZnO NPs p ncy ( a-43, b-
ize
e
the morpho laser fluenc of low laser and pressur in homoge
(a)
(b)
(c) prepared at 1
-71, c-142) J
Int. J. Nanoe
logy contro cy on the sta
fluence (Fi re in additio enous densi
.06 m laser J/cm2 and 20
electronics and
olling by las ate of plasm
g. 4a) the p on to space ty distribut
r wavelength pulse.
Materials 6 (20
ser fluency ma, especial plasma plum e distributio
tion in plasm
h and differen
013) 121-128
125 in present lly the life me is weak n of laser ma plume
nt laser
Evan T. Salem, et al. / Metal oxide nanoparticles suspension for optoelectronic devises fabrication
126
In such liquid environment within homogeneously distributed species the plasma is strongly affected by liquid media and laser fluence, so the pre formed ZnO cluster incline to self-assemble into different shape Nanoparticles from flack like structure, helical structure to spherical nanoparticles and this result is in consistence with other work [8,4]. Fig. 5 show the surface morphology of direct spraying ZnO nanoparticle colloidal on glass substrate at (60 Co) resulted in highly uniform ZnO Nanoparticles thin film. In this case 1.06 m laser wavelength with (71) J/cm2 laser fluency was used to the preparation of ZnO colloidal suspension with an average grain size of about (34.06) nm which are very close to the value of the grain size of sample prepared at same laser fluency and its drop drying on glass substrate Fig. 4a. Surface roughness of spraying thin film is about (0.214 nm) which reflect a high quality thin film. Such result open a new gate toward introduced such colloidal in to optoelectronic application, e.g fabrication of thin films solar cell detectors, and others. to describe the heterojunctin performance.
Fig. 5: Surface morphology of ZnO NPs thin film prepared by direct spraying using 1.06 m laser, (28) J/cm2, and (20) laser pulses.
Fig. 6 decribes the results of the current-voltage (I-V) measurements in the dark for the prepared heterojunctions. Where current-voltage characteristics of the ZnO/p-Si heterojunctions in theforward and reverse bias is shown. In forward biase, Two regions are recognized; the first one represents recombination current while the second represents the tunneling current. In the reverse bias, It is clear that the curve contains two regions; the first is the generation region where the reverse current is slightly increased with the applied voltage and this leads to generate electron-hole pairs at low bias
Average particle diameter 34.06(nm)
Int. J. Nanoelectronics and Materials 6 (2013) 121-128
127 Fig. 6: I-V charecteristics for ZnO\P-Si heterojunction device.
In the second region, a significant increase can be recognized the reverse bias is increased. In this case, the current is resulted from the diffusion of minority carriers through the junction. We can also note from this figure the rapid increment in the reverse current at high reverse voltage, which is probably due to the leakage current arising from the surface layer. The photocurrent is a very important in photodetector and heterojunctin performance.
The current-voltage (I-V) measurements in the illumination for ZnO/p-Si heterojunction is shown in Fig. 7. This figure shows the behavior of the current as a function of the applied reverse bias voltage with different illumination powers, operating the detector under external revers bias causes the deplation region to be extended. So, a large photon number of incident beam transmited through the ZnO layar and absorbed mainly in the deplation region, creating electron-hole pair's generation that generated photocur. As the result, the internal electric fields in the depletion region cause separation of the electron and the holes, this electric field is much higher when the device in the reverse bias. So, when the incident power density increased the absorbed photo number becomes greater and large number of electron-hole pair is generated, also it shows that the current reashes a saturation value at higher bias voltage because the electric field is strong enough to separate any generated pair for certain incident power
.
Fig. 7: Dark I-V charecteristics under reverse bias for ZnO\Si heterojunction device.
‐300
‐200
‐100 0 100 200 300 400 500
‐4 ‐3 ‐2 ‐1 0 1 2 3 4
dark current (A)
baise voltage (Volt)
‐3000
‐2500
‐2000
‐1500
‐1000
‐500 0
‐3.5 ‐3 ‐2.5 ‐2 ‐1.5 ‐1 ‐0.5 0
photocurrent (A)
baise voltage (volt)
0.11 mW.cm‐2 0.27 mW.cm‐2 0.59 mW.cm‐2 0.96 mW.cm‐2 2.3 mW.cm‐2
Evan T. Salem, et al. / Metal oxide nanoparticles suspension for optoelectronic devises fabrication
128
4. Conclusion
Photovoltaic optoelectronic device was sucssfuly fabricated usin ZnO Nanoparticles suspension. The result show a direct dependent of the prepared Nanoparticles on the laser parameters. XRD analysis show that the monocrytaline structure of condence ZnO nanoparticles increase with laser flunce. Morphology of dryed suspension shows that the particles size increases with increasing the laser fluency, Electrical preoerties of the prepared devise show good rectification and photorespose.
References
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